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|TUESDAY, JANUARY 18, 2000 - A RARE JANUARY TORNADO
When you think of tornadoes, you usually don't think of January - since 1950, only one tornado has been reported in Delaware in January and only five in Pennsylvania.
But last year on this date, a weak tornado touched down in South Philadelphia, with winds estimated between 40 and 70 mph. The tornado was about 20 yards wide, was on the ground for 300 yards, and caused 18 injuries.
Temperatures that day were warm for January - near 60 - and this tornado formed at the boundary where rain-cooled air coming down out of a thunderstorm clashed with this relatively mild air already in place.
Meteorologists call this boundary a "gust front", and tornadoes that form along it, "gustnadoes". Last year's weak tornado on this date was a gustnado.